Cross-linking coating polymers with polysulfonazides



United States Patent 3,352,798 CRQSS-LINKHNG CUATENG POLYMERS WETH PULYSULFDNAZIDES David S. Breslow and Frank E. Piech, Wilmington, DeL, assignors to Hercules Incorporated, a corporation of Delaware No Drawing. Filed June 17, 1964, Ser. No. 375,947 12 Qlaims. (Cl. 2602) This invention relates to cross-linking polymers and to the vulcanizates so produced. More particularly, the invention relates to cross-linking certain coating polymers with polysulfonazides.

Nitrocellulose, ethyl cellulose, saturated alkyds, triallyl pentaerythritol derivatives, chlorinated rubber, poly (ethylene oxide) and vinylidene chloride-acrylonitrile copolymers are well known for their ability to be formulated into coating compositions. However, the end products all sulTer a serious drawback in that they tend to be soft, soluble in most organic solvents, and low in chemical and heat resistance.

It has now been discovered that the above polymers can be cross-linked by heating in the presence of a polysulfonazide to produce vulcanizates that are solvent resistant, have increased hardness, stillness, and chemical and heat resistance.

The polymers which can be cross-linked in accordance with this invention are nitrocellulose, varying in nitrogen content from 10.5 to 13.5 percent and varying in viscosity from sec. to 100 sec. (ASTM D 301-56), ethyl cellulose, the saturated alkyl resins, including coconut oil modified phthalic alkyds, and castor oil modified sebacic acid alkyds, chlorinated rubber as described in US. Patents 1,826,275, 2,275,469, 2,375,958, 2,382,353, 2,401,- 133 and 2,401,194, poly(ethylene oxide), the triallyl pentaerythritol ethers, such as the diallylidene pentaerythritol ether of triallyl pentaerythritol, the triallyl pentaerythritol esters such as the linseed acid ester of triallyl pentaerythritol, and vinylidene chloride-acrylonitrile copolymers.

Any polysulfonazide, i.e., any compound having the general formula R(SO N where R is an organic grouping inert to the cross-linking reaction and x is an integer greater than 1, can be used in the process of this invention. Preferably, x will be an integer from 2 to 100 and -R will be selected from the group of organic radicals consisting of alkylene, arylene, aralkylene, and alkarylene radicals, however, these radicals can also contain ether,

2,4,6-benzene tris(sulfonazide), 4,4'-diphenylmethane bis (sulfonazide), ot,oc' m xylene bis(sulfonazide), 4,4'-diphenylether bis(sulfonazide), 4,4-bis octadecyl biphenyl- 3,5,3,5' tetra(sulfonazide), 4,4 diphenyldisulfide bis (sulfonazide), 1,6-bis(4'-sulfonazidophenyl) hexane, 2,7- naphthalene bis(sulfonazide), polysulfonazides of chlorinated aliphatic hydrocarbons, etc.

The cross-linking process of this invention can be carried out by heating the polymer plus the polysulfonazide to a temperature at which the sulfonazide decomposes. The temperature will Vary over a Wide range, but in general will be in the range of from about 100 C. to about 250 C. Various amounts of the cross-linking agent can be added, the optimum amount depending on the amount of cross-linking desired, the specific sulfonazide employed, etc. In general, the amount added, based on the weight of the polymer, will be from about 0.1% to about 25%.

The cross-linking agent can be incorporated with the polymer in any desired fashion. For example, it can be uniformly blended by simply milling, dissolved or dispersed in a solution containing the polymer, or dissolved or dispersed in a latex containing the polymer. By these means, the polysulfonazide is distributed throughout the polymer and uniform cross-linking is elfected when the blend i subjected to heat. Other methods of mixing the cross-linking agent with the polymer will be apparent to those skilled in the art.

In addition to the cross-linking agent, other ingredients can be incorporated in the polymer. Exemplary of such ingredients are extenders, fillers, pigments, dyes, plasticizers, driers, stabilizers, etc. Obviously, there are many cases in which these ingredients are not required or desired, and excellent results are achieved when only the cross-linking agent is added.

As stated above, the use of polysulfonazide cross-linking agents is particularly advantageous in coating compositions prepared from the above polymers.

The following examples are presented for purposes of illustration, parts and percentages being by weight unless otherwise specified. A solubility test was used in the examples to evaluate the ellectiveness of the polysulfonazides as cross-linking agents. Cross-linked compositions are no longer soluble in active solvents.

EXAMPLES 1-3 Three sample of nitrocellulose coating compositions were cross-linked with diiferent disulfonazides. The formulation of each sample is shown in Table I.

I TABLE I Example Number Ingredients 1A 1B 2 2A 2B 3 3A 313 N itrocellulose 1 (parts) 20 20 20 14 Coconut oil (parts) 20 2O 20 Drying alkyd 2 (parts). 42 N ondrying alkyd 3 (parts) Toluene (parts) 30 30 30 21 Ethanol (parts) 9 9 9 7 Ethyl acetate (parts) 9 9 9 v 7 Butyl acetate (parts) 12 12 12 9 Phenyl-B-naphthyl-amine (anti-oxidant) (parts). 1.1 1,10-decane bis (sulfonazide) 4 (parts). 4 1,3-benzene bis (sulfonazide) 4 (parts) 4 1 Contains 12% nitrogen and has a viscosity, by the falling ball method, of second. 2 Glyceryl phthalate alkyd modified with 56% linseed oil (100% solids). 3 Pentacrythritol phthalate alkyd modified with coconut oil (60% solids in toluene).

4 Dissolved in acetone.

alcohol, etc., groups which are inert to the cross-linking reaction. Exemplary sulfonazides are 1,5-pentane bis(sulfonazide), 1,10-decane bis(sulfonazide), 1,4-cyclohexane bis(sulfonazide), 1,3-benzene bis(sulfonazide), l-octyl- The resulting compositions were spread on glass plates and allowed to air dry. Then they were baked at a temperature of C. Each of the resulting films was tested for solubility by tumbling for 18 hours in butyl acetate at 3 4 a temperature of 25 C. (1 gm. film in 100 ml. of solvent). TABLE In The period of time the films were baked and their solubility is tabulated below. Example Number Ingredients Period of Example Number 6 6A 6B 7 7A 7B baking (hrs.)

1 1A 1B 2 2A 2B 3 3A 3B Ether of dlallylidene pentaerythritol with triallyl pentae rythritol (parts) 10 10 1 u 8* I S I S I Ester of triallyl pentaerytn- 2 S I S I S I ritol and linseed acids 10 (parts) 10 10 10 K Plienyl fl-naphthylamine S=s01ub1e,.I=1nsoluble. (anti-oxidant) (parts) 0.2 0.2 0.2 0.2 0.2 0.2

1,1 r 2 EXAMPLE 4 AND 5 .2ifi?i.iif??? 0.1 0.1

. Lil-benzene bis (sulionazide) 2 Two samples of saturated alkyd baking enamels were (parts) 0.1 0.1 cross-linked with different disulfonazides. The formulation of each sample is shown in Table II. 1 Reacted in a ratio of 1 mole o1 diallyidene pentaerythritol to 2 moles of triallyl pentaerythritol. TABLE H z Dissolved in acetone.

Example Number Ingredients Nondrying alkyd. (parts) The resulting compositions were spread on glass plates g y s alkyd2 (p 3 3 8 3 8 1; and allowed to a1r dry. Each sample was then baked at 93.13, ifi fifiagg gggggggga'" a temperature of 150 C. and tested for solubility by (parts) 0.1 0.1 t m ratur of IMenmne bis (sulfonazide) 3 tumbling for 18 hours n butyl acetate a a te pe e (parts) 0.1 0.1 25 C. (1 gm. of film 1n 100 ml. of solvent). The period Pentaerythritol phthalate alkyd modified with coconut oil (60% a solids in toluene).

2 Sebacic acid alkyd modified with castor oil solids in toluene).

3 Dissolved in acetone.

The resulting enamels were spread on glass plates and allowed to air dry overnight. Each sample was then baked at a temperature of 150 C. and tested for solubility by tumbling for 18 hours in a solvent at a temperature of of time the films were baked and their solubility is tabulated below.

Example Number Period of baking 25 C. (1 gm. of film in 100 ml. of solvent). The period of time the films were baked, the solvent in which they 6 6A 6B 7 7A 78 were tested and their solubility is tabulated below. 8 I S I s i s 'i Example Number 4 4A 4B 5 5A 5B Test Solvent Butyl acetate Toluene Period of baking EXAMPLES 8-11 S I S u I Four samples of ethyl cellulose coating compositions s I S I 50 were cross-linked with different disulfonazides. The formulation of each sample is shown in Table IV.

TABLE IV Example Number Ingredients 8 8A 8B 9 9A 9B 10 10A 10B 11 11A 11B Ethyl cellulose 1 (parts) 15 15 15 15 15 15 10 10 10 15 15 15 Coconut oil (parts) 15 15 15 Nondrying alkyd 2 (parts) 1- 15 15 15 Parafiin wax (parts)- 10 10 10 Mineral oil (parts).-- 15 15 15 Toluene (parts) 56 56 56 56 5e 56 32 32 32 so 56 5o Ethanol (parts) 14 14 14 14 14 14 8 8 8 14 14 14 Carbon tetrachloride (parts). 40 40 40 1,10decane bis(su1fonazide) (parts) 3 3 2 3 1,3-benzene bis(su1t'onazide) (parts) 3 3 2 3 1 Having an etho yl content of approximately 48.25% and a viscosity of approximately 9.5 cps. 2 Commercial rosin derived alkyd type resin (softening point -76 0.).

3 Dissolved in acetone.

EXAMPLES 6 AND 7 Two samples of 'triallyl pentaerythritol derivatives were cross-linked with different disulfonazides. The formulation of each sample is shown in Table III.

The resulting compositions were spread on glass plates and allowed to air dry. Each sample was then baked at a temperature of 150 C. and tested for solubility by tumbling for 18 hours in a mixture of parts of toluene and 20 parts of ethanol at a temperature of 25 C. The period of time the films were baked and their solubility is tabulated below.

The resulting compositions were spread on glass plates and allowed to air dry. Each sample was then baked at a temperature of 150 C. and tested for solubility by Period of baking (hrs) E xample Number 8 I 8A 8B 9 9A 9B 10 11A 11B 1 S I S I S I 2 S I S I S I EXAMPLES 12-17 Six samples of chlorinated rubber coating compositions were cross-linked with different disulfonazides. The formulation of each sample is shown in Table V.

tumbling for 18 hours in methyl ethyl ketone at a temperature of 25 C. The period Of time the films were baked and their solubility is tabulated below.

TABLE V Ingredients Example Number 13 'mjnl 14A}14B ins 15A 1 Having a chlorine content of approximately 67% and a viscosity of approximately 11.5 cps. 2 Containing 60 mole percent of methyl methaerylate and having a molecular weight of approximately 100,000. 3 Pentaerythritol phthalatc alkyd modified with coconut oil (60% solids in xylene).

4 Glyceryl phthalate alkyd modified with 55% 5 Dissolved in acetone.

The resulting compositions were spread on glass plates dehydrated castor oil (70% solids in xylene).

and allowed to air dry. Each sample was then baked P riod 0ftime(hr5.) 18 18A 18B at a temperature of 150 C. and tested for solubility by tumbling for 18 hours in toluene at a temperature of 1 S I C. The period of time the films were baked and their 2 S I solubility is tabulated below.

Example Number Periodlof lgaking rs 12 12A 13 i 13A 14 14A 14B 15 15A 15B 16 16A 17 17A 17B 1 s I s I s I s I s I s I 2 s I s I s I EXAMPLE 18 EXAMPLE 19 A sample of poly(ethylene oxide) having a molecular weight of approximately 100,000 was cross-linked with 1,3-benzene bis(sulfonazide) in the following formulation.

rm lat n 0 ea h sam 1c is sh wn below. to u 10 f c p o 19 19A Example Number P01 y(ethylene oxide) (parts) 10 Ingledlents Benzene (parts) 40 18 18A 18B 1,3-Benzene bis(sulfonazide) (parts) 1. 0

Vinylidene cl1lorideaciylonitrile copolymer 1 Dissolved in acetone (ESTESf1 ai. t E i8 50 18 The resulting compositions were spread on glass plates 1e ye y eonepars Lloflecane bissulfonazidefiwarts)" 1.0 and allowed to air dry. Each sample was then baked 1,3-benzene bis(sulfonazide) (parts) 1.0 for 1 hour at a temperature of C. The resulting films were tested for solubility by tumbling for 18 hours 1 Dissolved in acetone.

in benzene at a temperature of 25 C. The sample containing the disulfonazide (19A) was insoluble while the control (19) was completely soluble.

What we claim and desire to protect by Letters Patent 1. A process of cross-linking a polymer selected from the group consisting of nitrocellulose, ethyl cellulose, saturated alkyd resins, triallyl pentaerythritol ethers, triallyl pentaerythritol esters, chlorinated natural rubber, poly(ethylene oxide), and vinylidene chloride-acrylonitrile copolymers, which comprises heating said polymer at a temperature of from about 100 C. to about 250 C. in admixture with from about 0.1% to about 25% by weight of a polysulfonazide cross-linking agent having the formula .R(SO N where x is an integer greater than 1 and R is an organic radical inert to the cross linking reactions.

2. The process of claim 1 wherein the polymer is nitrocellulose.

3. The process of claim 1 wherein the polymer is ethyl cellulose.

4. The process of claim 1 wherein the polymer is a saturated phthalic acid alkyd.

5. The process of claim 1 wherein the polymer is a triallyl pentaerythritol ether.

6. The process of claim 1 wherein the polymer is a 25 triallyl pentaerythritol ester.

7. The process of claim 1 wherein the polymer is a chlorinated natural rubber.

8. The process of claim 1 wherein the polymer is poly (ethylene oxide).

9. The process of claim 1 wherein the polymer is vinylidene chloride-acrylonitrile copolymer.

10. The process of claim 1 wherein the polysulfonazide is 1,10-decane bis(sulfonazide).

11. The process of claim 1 wherein the polysulfonazide is 1,3-benzene bis(sulfon,azide).

12. A polymer selected from the group consisting of nitrocellulose, ethyl cellulose, saturated alkyd resins, triallyl pentaerythritol ethers, triallyl pentaerythritol esters, chlorinated natural rubber, poly(ethylene oxide), and vinylidene chloride-acrylonitrile copolymers crosslinked with a polysulfonazide having the formula R(SO N where x is an integer greater than 1 and R is an organic radical inert to the cross-linking reactions.

References Cited UNITED STATES PATENTS 3,137,745 6/ 1964 Johnstone 2602 3,211,752 10/1965 Breslow 2602.5 3,261,785 7/ 1966 Robinson 260349 OTHER REFERENCES Handbook of Chemistry by Lange, N., 8th ed., 1952 (page 814 relied on).

WILLIAM H. SHORT, Primary Examiner.

3 T. PERTILLA, Assistant Examiner. 

1. A PROCESS OF CROSS-LINKING A POLYMER SELECTED FROM THE GROUP CONSISTING OF NITROCELLULOSE, ETHYL CELLULOSE, SATURATED ALKYD RESINS, TRIALLYL PENTAERYTHRITOL ETHERS, TRIALLYL PENTAERYTHRITOL ESTERS, CHLORINATED NATURAL RUBBER, POLY(ETHYLENE OXIDE), AND VINYLIDENE CHLORIDE-ACRYLONITRILE COPOLYMERS, WHICH COMPRISES HEATING SAID POLYMER AT A TEMPERATURE OF FROM ABOUT 100*C. TO ABOUT 250*C. IN ADMIXTURE WITH FROM ABOUT 0.1% TO ABOUT 25% BY WEIGHT OF A POLYSULFONAZIDE CROSS-LINKING AGENT HAVING THE FORMULA R(SO2N3)X WHERE X IS AN INTEGER GREATER THAN 1 AND R IS AN ORGANIC RADICAL INERT TO THE CROSSLINKING REACTIONS. 